The invention relates to the web manufacturing industry. Materials like paper, films and various laminates are typically manufactured as a continuous sheet or web of material. During the processing of a continuous web, the web is handled by cylindrical rolls and cut into continuous strips. This cutting is typically required for downstream handling or for producing a final product such as a roll of tape.
The instant invention is an accessory for use on a typical slitting device. The slitting device includes a sharp circular blade and a blade actuator referred to as a knifeholder. The knifeholder typically includes a means of extending and translating the circular blade into an anvil or cutting edge. The invention is a guard that covers the blade while the slitter is not engaged with the anvil or cutting edge.
The prior art cited in U.S. Pat. No. 5,546,840 Dienes teaches a guard mechanism which is manually set and pivots along the circumference of the blade. This exposes the operator to the blade and the operator can be cut by the blade during handling. If the operator elects not to use the guard, for instance, the guard will not be covering the blade and he/she can easily be cut by the blade. Especially during maintenance when the knife holder is removed from supporting equipment.
Other prior art is cited which includes U.S. Pat. No. 4,905,424 Nagashima. This patent teaches the use of two side plates which are D-shaped to surround the exposed half of a circular blade. This invention requires the operator to connect the edges of the two side plates and so while the operator is attaching the two side plates he or she is exposed to the sharp edge of the blade.
U.S. Pat. No. 441,823 Ashbrook discloses a guard for a web slitter. This patent also teaches a two piece guard. One guard piece is attached to a body that supports a circular blade. This guard is manually adjustable along with the circular blade. A second guard piece overs all of the blade but a small cutting area. This cover is attached to the other guard by screws engaging slots on the second guard. These screws and slots are used to adjust the amount of blade exposed for cutting. In this case the blade is exposed during handling of the slitter.
U.S. Pat. No. 6,857,939 Adachi, teaches a guard mechanism that includes an interlock device. The guard mechanism consists of a static guard and a pivoting guard. The pivoting guard pivots away from the cutting edge of the blade about an axis that is parallel to the axis of rotation of the circular blade. This increases the amount of space required. The interlock device prevents a blade attaching and detaching device being attached when the cover is in a closed position. In this invention the blade is only guarded while attached to the slitting assembly and the cutting portion is still exposed to an operator.
U.S. Pat. No. 7,223,163 Neumeier, teaches a two piece guard in which a pivoting piece rotates about an axis parallel to the axis of rotation of the blade. This guard is also manually adjusted and so relies on the operator to extend the pivoting piece when the device is not in use.
U.S. Pat. No. 7,628,682 Andrasic, teaches a detachable guard. This guard consists of two sections, a cover section and an attaching section. The guard section is semi-circular in shape, the gripping section is attached to the guard section at the center of the semi-circular radius. The gripping section includes a handle which engages teeth and pivots into a locking position while gripping a cylindrical tool housing.
The applicant is also aware of a guard fitted to a slitter which was/is provided by Dienes. A patent covering this design was not found. This guard included a semi-circular piece, a flexible mounting for the semi-circular piece and features located on a vertical blade actuator. In this design the vertical actuator moves the blade vertically toward an anvil. During this movement the features on the actuator cause the guard to flex away from the blade. This movement allows the blade to extend toward the anvil and the guard simultaneously moves out of the way. This design however does not provide adequate protection for an operator. The flexible guard can easily be pushed in such a way to expose the cutting edge of the blade possibly injuring the operator.